March 23, 2010

Did Volcanoes Help Dinosaurs Ascend to Power?

Volcanic activity more than 200 million years ago may have helped dinosaurs become and remain the world's dominant species by causing the mass extinction of rivals, researchers claim in a recent study.

The paper, which was completed by a five-person team of researchers from the United States and Taiwan and published in the Proceedings of the National Academy of Sciences (PNAS), suggests that it was mass volcanic eruptions that wiped out the crurotarsans, the crocodile-like creatures that were the dinosaurs' chief competitors for food during the Triassic Period.

According to a March 23 article by BBC News science reporter Paul Rincon, the researchers "looked at several lines of evidence such as the remains of plant wax and wood from sedimentary rocks interbedded with lava flows. From these, they were able to extract vital data about the climate" during the late Triassic Period.

"The scientists examined how two different isotopes (or forms) of carbon fluctuated during these volcanic eruptions. They found that the 'heavy' form of carbon was depleted relative to the 'light' form," Rincon wrote. "The scientists have not yet determined the killing mechanism behind the mass extinction. Neither can they say for sure why the dinosaurs survived it."

Comprising the research team were Jessica H. Whiteside of the Brown University Department of Geological Sciences; Paul E. Olsenand Raymond N. Sambrotto of Columbia University's Lamont-Doherty Earth Observatory; Timothy Eglinton of the Department of Marine Geology and Geophysics at Woods Hole Oceanographic Institution; and Michael E. Brookfield from the Earth Sciences Academia in Sinica, Nankang, Taipei, Taiwan.

The abstract for their report, which was entitled " Compound-Specific Carbon Isotopes from Earth's Largest Flood Basalt Eruptions Directly Linked to the End-Triassic Mass Extinction" called the findings, "the strongest case for a volcanic cause of a mass extinction to date."


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